Their platform, their rules. If the rights group needs to publish videos, they should create their own platform.
Companies that interact with society need regulation as does YouTube. Its going to be hard to balance the freedom of expression vs what is harmful. In what is a grey zone I feel encouraging violence is the best line, and letting the courts sort out defamation.
But that's where we are, and after this incident we'll merely negatively adjust our perceptions of Google and continue to use their services.